(a) Field
Embodiments relate to a circuit for preventing repetition of an overvoltage and a method thereof. Also, Embodiments relates to a power factor correction circuit using an overvoltage repetition prevention circuit and a method thereof.
(b) Description of the Related Art
In a system in which a control response for a change of an output voltage is slow, the output voltage may be increased to an overvoltage. As one example of the system in which the control response is slow, there is a power factor correction circuit.
In a normal state in which the output voltage of the power factor correction circuit is controlled to be constantly maintained, when the input voltage of the power factor correction circuit is increased or a load connected to the power factor correction circuit is decreased, the output voltage may be increased to the overvoltage.
The power factor correction circuit receives a feedback voltage corresponding to the output voltage and controls the output voltage according to the feedback voltage to control the output voltage to be constant. Here, a fluctuation generated to an AC line connected to an input terminal of the power factor correction circuit must be reflected to the output voltage.
The output voltage must be constantly generated and the input current of the power factor correction circuit must be controlled to follow the sine wave for the power factor correction. Generally, for this, it is set up that a control loop speed of the power factor correction circuit is slow.
If the overvoltage is generated, a switching operation of the power factor correction circuit is stopped and the stop state of the switching operation is maintained until the output voltage is decreased to a predetermined threshold voltage (an overvoltage determination reference voltage). This is referred to as an overvoltage protection operation.
Although the output voltage is less than the threshold voltage and then the switching operation is again started, the feedback voltage determined according to the level of the output voltage enters a high state by the slow speed of the control loop. Accordingly, the overvoltage may again be repeatedly generated. Thus, the overvoltage protection operation may be repeatedly generated.
As described above, if the overvoltage is repeatedly generated such that the overvoltage protection operation is triggered, the overvoltage protection operation is repeatedly generated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.